.a {
  color: red;
}
.mixin-class {
  color: red;
}
.my-mixin {
  color: black;
}
.class {
  color: black;
  background: white;
}
button:hover {
  border: 1px solid red;
}
#header {
  -webkit-border-radius: 4px;
  -moz-border-radius: 4px;
  border-radius: 4px;
}
.button {
  -webkit-border-radius: 6px;
  -moz-border-radius: 6px;
  border-radius: 6px;
}
.unimportant {
  background: #f5f5f5;
  color: #900;
}
